The ability to measure a wide variety of physiologically active compounds, both naturally occurring and synthetic, has become of increasing importance, both as an adjunct to diagnosis and therapy. While for the most part, assays of physiological fluids and drugs have required clinical laboratory determinations, there is an increasing awareness of the importance of being able to carry out assay determinations in the doctor's office and in the home. To be able to perform an assay in a doctor's office or home requires that an assay have a simple protocol and be relatively free of sensitivity to small changes in the conditions under which the assay is carried out. Importantly, accurate measurements of reagents and sample should whenever feasible be avoided. Numerous systems have been developed in efforts to try to address the various problems associated with analysis outside of the clinical laboratory. There is, nevertheless, a continuing interest in providing improved and alternative methods to those which are presently generally available.
Exemplary of this situation is the need today to be able to determine cholesterol levels or low density protein levels in blood. There is a clearly established relationship between total blood cholesterol (mainly LDL fraction) and coronary artery disease (Journal of the American Medical Association (1985) 253:2080-2086). New guidelines have been established for adults over 20 years of age to identify risk groups associated with blood cholesterol level. These levels are as follows: &lt;200 mg/dl is a desirable blood cholesterol; 239 mg/dl is borderline high blood cholesterol; &gt;240 mg/dl is high blood cholesterol.
Cholesterol levels can be controlled by both diet and cholesterol lowering drugs. The key is to identify those individuals at risk. By being able to monitor one's own cholesterol at home for those individuals at risk will provide a significant tool in monitoring cholesterol levels and reducing the potential for heart disease. The measuring of other naturally occurring compounds of physiologic importance and synthetic drugs is also of great interest.